1. Cross Reference to Related Applications
This application is related to Assignee's copending application Ser. No. 08/557,980 filed Nov. 13, 1995.
2. Field of the Invention
Bioremediation of dissolved hydrocarbons in ground water by increasing the amount of dissolved oxygen in the ground water resulting in enhanced biodegradation by aerobic microbes.
3. Background Art
U.S. Pat. No. 4,950,394 to Bernhardt et al relates to an arrangement for driving out volatile impurities from the ground water and from ground through which it flows. More particularly, it relates to the arrangement in which the driving out is performed by producing a negative pressure in a well shaft extending to the region of the contaminated ground water and supplying a gas, especially fresh air, underneath the water level of the well shaft. The limiting wall of the well shaft is provided, at least in the region between the air inlet and the water table, with a plurality of fine capillary openings which produce a laminar liquid flow with relatively high speed, and a greater free throughflow or passage surface than in a remaining region of the limiting wall of the well shaft.
In U.S. Pat. No. 5,332,333 to Bentley, volatile contaminants are removed from the vadose zone of contaminated earth by vacuum extraction through a borehole placed into the contaminated area. Means are provided for substantially trapping water within the extraction borehole so as to prevent contaminated water from being brought to the surface. Means are also provided for maintaining substantially atmospheric pressure at the bottom of the extraction borehole so as to prevent water from the water table from rising into the borehole and to allow improved circulation of air through the contaminated zone. Preferably the conduit is kept open and pressure is maintained by passive infiltration of atmospheric air into the bottom of the conduit but, if desired, air may be injected into the conduit by positive pressure means.
U.S. Pat. No. 5,358,357 to Mancini et al discloses a process and apparatus for high vacuum groundwater extraction in which the gas inlet is generally situated at a level below the natural water table but above the level to which the groundwater drops after the pumping process has been in operation for a period of time.